I think too the main problem of an early ...f5 is the various g4-tries which can be pretty dangerous if White gears towards this plan (& O-O-O) right from the start of the game.

I think the most accurate move order for Black is as given by kylemeister in his first post. This of course means that Black will be willing to face the Marshall gambit with 4. e4 (dangerous but I don't tend to face this one often).

re the discussions of ...Be7 set-ups: may work well against Bf4 or Bg5. Of course Bd6 is more attacking and has better control over e5, but you can still generate powerful attacks with the ...Be7 set-up. The way I see it, the main problem of ...Be7 is b3 & Ba3xBe7 (in the ...Bd6 set-up ...Qe7 defends against this).

The configuration Bf4 vs. ...Bd6 may favour either player (for instance with ...Bd6 already played: g3/O-O/Bf4 => ...BxBf4 is good for Black, while on the contrary with g3/Bf4 => ...BxBf4?! would invite O-O-O). Also, in general terms  Black would like to avoid an 'unpunished' Bf4xBd6 swap, parting with his/her good Bishop.

Kyle, Black hasn't played c6. He plays f5 before c6. 

This move order is indeed rare in large measure because of White's Bf4. However, I think Kramnik showed that Black still has plenty of play even with the B on e7. (I didn't go back and look at his article on the Stonewall in answering this question.)

So, there are two main reasons that Black rarely plays 3...f5: 

1: The Stonewall isn't a great winning attempt, so there are relatively few people who want to try this line.

2: The move order limits Black perhaps even more than it limits white in that the Bd6 lines should favor white after 4.Bf4. This means that Black must be willing to play 4...Be7 variations.

So I'm messing around with some new openings against d4 lately, and the Albin Counter-Gambit seems like it could be fun after 1.d4 d5 2. c4. But I wasn't sure what to play if white doesn't play 2. c4. I've been thinking of trying out the Stonewall Dutch, so I thought maybe I can use that against non-QG openings, alongside the Albin. I just haven't figured out the best move order.

Are there any pitfalls to look out for when continuing with e6 and f5 after 1. d4 d5? 

I'm thinking an early Bf4, as in the London System, might mess up the typical Bd6 in the Stonewall. So maybe I could play e6 first, and wait until after Bd6 to play f5, just to avoid the Stonewall formation if I can't play Bd6. Of course, that leaves me wondering what to do against the London, which is pretty popular around here. 

Now I'm wondering if maybe this belongs in the d pawn specials section, instead.